Lidded drums are generally known as including a drum body with an outer wall and an essentially radially protruding casing flange at some distance from the top end of the drum opening. The flange acts as a counter-bearing for a clamping member. The plastic drum lid has a U-shaped lid rim, whose outer rim wall grips over the top of the outer wall of the drum body and as far down as its casing flange. An essentially radially protruding lid flange runs all around the outer rim wall of the lid rim for cooperating with the casing flange. The rim also includes an inner rim wall extending through the drum opening and for a distance, essentially parallel and near to the inside surface of the outer wall of the drum. A sealing ring disposed in the lid rim seals against the top end of the drum opening. When the drum is closed, the clamping member extends over both the casing flange and the lid flange. Such lidded drums are generally known to persons skilled in the art as they are used all over the world. This standard lidded drum, developed by Mauser, is described in the U.S. Pat. No. 4,177,934.
Certain requirements regarding storage and transport safety are imposed on lidded drums. They require testing and verification in special approval tests (e.g. side fall on the casing side, diagonal fall on the lid rim, static inside pressure test, etc.). With previous known plastic lidded drums, the drum lid can become loose under certain conditions, especially in the case of liquid fills. The drum lid can even jump off completely when the drum topples from heights of about 1.20 m, e.g. from the platform of a truck.